Lipid peroxidation and acetylcholinesterase activity as biomarkers in the Black Sailfin Goodeid, Girardinichthys viviparous (Bustamante) exposed to water from Lake Xochimilco (Mexico)

Lake Xochimilco has been the receiver of untreated domestic wastewater, agricultural run off and secondary effluent of a treatment facility, thus becoming the receptor of a mixture of pollutants and their metabolites. Major zones in Lake Xochimilco are urban, agricultural and tourist; all of them exert environmental pressure to the Lake, that has been associated with the extinction of two fish species, and the limited presence of another, Girardinichthys viviparous. Early warning biomarkers of G. viviparous were analyzed after its reintroduction to waters of Lake Xochimilco, in order to evaluate the responses of the fish in the case of their repopulation in their ancient habitat. We examine some indicators of the water quality, the level of lipid peroxidation and the acetylcholinesterase activity in brain, gill, liver and muscle of G. viviparous after exposure to waters of each zone of Lake Xochimilco. The results show that the urban area presents an enrichment of ammonium, related to the sewage; the agricultural zone apparently had the highest concentrations of phosphorous, perhaps derived from the use of fertilizers; and the tourist zone reached elevated values in chlorophyll and turbidity. Differences were detected in lipid peroxidation and the acetylcholinesterase among the sites and tissues tested. The urban and agricultural zones, produced increases in the lipid peroxidation in muscle, brain, liver and gills. Acetylcholinesterase shows an inhibition in the function of the brain, liver and gills of fish exposed to agricultural waters; however, the muscle shows an increase in all the sites. The observed effects might have health implications for the species studied, although further research would be required.